Method and apparatus for triangulation-based 3D optical profilometry

摘要

A method for determining a centerline for a triangulation-based optical profilometry system, compensating for the spatial variations of the reflectance of an object's surface. The method comprises providing a luminous line on the object, the luminous line being a triangulation line superposed with a compensation line; capturing an image of the triangulation line and of the compensation line; for each position along the imaged triangulation line, determining a transverse triangulation profile from the imaged triangulation line and a transverse compensation profile from the imaged compensation line; determining a transverse correction profile given by the reciprocal of the transverse compensation profile; multiplying the transverse triangulation profile with the transverse correction profile to obtain a corrected transverse triangulation profile; computing a center of the corrected transverse triangulation profile. The centers determined at positions along the triangulation line form the centerline. Embodiments of a triangulation-based optical profilometry system integrating the method are disclosed.

主权项

1. A method for determining a centerline for a triangulation-based optical profilometry system, said method compensating for spatial variations of reflectance of a surface of an object to be scanned with said triangulation-based optical profilometry system, said method comprising:
providing a luminous line on said surface of said object, said luminous line being a superposition of a triangulation luminous line generated by a triangulation light beam with a compensation luminous line generated by a compensation light beam, said triangulation light beam and said compensation light beam being collinear, said triangulation light beam having a lower étendue than said compensation light beam, said triangulation light beam having a nearly Gaussian irradiance profile along a transverse dimension; capturing a triangulation image of said triangulation luminous line, said triangulation image including an imaged triangulation luminous line; capturing a compensation image of said compensation luminous line, said compensation image including an imaged compensation luminous line; for each of a plurality of different positions defined along a length of said imaged triangulation luminous line,
determining a transverse triangulation profile from said imaged triangulation luminous line;determining a transverse compensation profile from said imaged compensation luminous line;determining a transverse correction profile by calculating the reciprocal of said transverse compensation profile;multiplying said transverse triangulation profile with said transverse correction profile to obtain a corrected transverse triangulation profile;computing a center of said corrected transverse triangulation profile and storing said center in a vector; and determining said centerline for said triangulation-based optical profilometry system from said vector.